1. Field of the Invention
The present invention relates to a magnetic head mounted on, for example, a hard disk drive, and comprising a slider, and particularly to a magnetic head wherein the starting force required for starting a recording medium is decreased, and at the same time, a thin film element provided on the trailing side end of a slider can be protected from contact with the recording medium, and a production method thereof.
2. Description of the Related Art
FIG. 8A is a plan view showing a magnetic head mounted on a hard disk with a surface opposite to a recording medium upward, FIG. 8B is a sectional view of the magnetic head shown in FIG. 8A taken along line VIIIBxe2x80x94VIIIB of FIG. 8A, and FIG. 8C is a sectional view of the magnetic head shown in FIG. 8A taken along line VIIICxe2x80x94VIIIC of FIG. 8A.
In the magnetic head H shown in these drawings, the upstream side (a) in the movement direction X of a disk is referred to as the leading side, and the downstream side (b) is referred to as the trailing side. A slider 1 comprises a ceramic material, and rails 4 are formed on both sides of an air groove 7 in a portion of the slider 1 opposite to the disk. As shown in FIG. 8B, each of the rails 4 has a convex sectional shape, and an opposite surface (air bearing surface; ABS) 5 is formed at the top of the convex sectional shape of each of the rails 4 so as to contact the recording surface of the disk when the magnetic head H is stopped. Each of the opposite surfaces 5 is processed to a crown shape with a predetermined curvature. As shown in FIG. 8C, each of the rails 4 has an inclined surface 6 formed at the leading-side end thereof.
As shown in FIGS. 8A and 8C, at the end 2 of the slider 1 on the trailing side (b) thereof are provided a thin film element 3 and a protecting film 8 for covering the thin film element 3. The thin film element 3 comprises a MR head (reading head) for detecting a fringing magnetic field to read a magnetic signal, and an inductive head (writing head) having a coil patterned thereon. The protecting film 8 comprises a non-magnetic ceramic material, e.g., aluminum oxide (Al2O3) or the like.
The slider 1 of the magnetic head H is supported by a flexure fixed at the tip of a load beam comprising a leaf spring so as to be urged on the disk by the elastic force of the load beam. The magnetic head H is used for a so-called CSS (Contact Start Stop) system hard disk device in which when the disk is stopped, the opposite surfaces 5 of the slider 1 contact the recording surface of the disk due to the elastic force. When the disk is started, a flow of air is guided into between the slider 1 and the surface of the disk along the movement direction (X direction) of the disk, and the opposite surfaces 5 are subjected to floating force of the flow of air to float the slider 1 at a short distance from the surface of the disk.
In the floating state, the slider 1 is in an inclined state wherein the leading side (a) rises from the disk more than the trailing side (b). In this floating state, the MR head of the thin film element 3 detects a magnetic signal from the disk, or the inductive head writes the magnetic signal.
A disk driving motor provided on the CSS system hard disk device requires starting torque sufficient to securely start the disk and the slider sliding. When the starting torque required for starting the disk and the slider is increased, a large motor must be used for the hard disk drive, thereby limiting miniaturization of the device and causing the problem of increasing power consumption.
The torque required for starting the disk depends upon the static frictional force between the opposite surfaces 5 of the slider 1 and the disk surface. In order to decrease the starting torque required for starting the disk, it is necessary to decrease the static frictional force.
In a conventional hard disk serving as a recording medium, since the disk surface has relatively high roughness, even if the opposite surfaces 5 of the slider are relative smooth surfaces, it is possible to decrease the real contact area between the disk surface and the opposite surfaces 5, and consequently possible to decease the static frictional force.
However, a recent hard disk for high-density recording has had the tendency that the disk surface becomes smooth. The reason for this is that when the surface of the hard disk is roughed, protrusions are nonuniformly formed on the disk surface, and thus the slider 1 in a floating state collides with the protrusions on the disk surface to damage the disk surface during magnetic recording or reproduction by the magnetic head. When the slider 1 repeatedly collides with and contacts the protrusions on the disk surface, the thin film element 3 mounted at the end 2 of the slider 1 is damaged, thereby deteriorating recording and reproduction performance. In addition, heat is generated by collision and contact between the slider 1 and the disk surface, thereby causing the problem of generating noise in the reproduced output. Particularly, in a hard disk for high-density recording, it is necessary to decrease the spacing between the thin film element 3 and the disk surface, and thus avoid the formation of irregular protrusions on the disk surface. Therefore, the hard disk for high-density recording tend to have a smooth disk surface close to a mirror surface.
When the disk surface of the hard disk is a smooth surface, the above problems can be solved. However, when both the disk surface and the opposite surfaces 5 of the slider are smooth surfaces, a lubricant or water film coated on the disk surface are present between the disk and the slider 1 when the hard disk device is stopped, and thus the slider 1 is adhered to the disk. Therefore, the static frictional force is increased when the disk is started, and large starting torque is thus required for starting the disk.
Therefore, in a hard disk device having a smooth disk surface for high-density recording, it is necessary to rough the opposite surfaces 5 of the slider 1 to decrease the real contact area between the opposite surfaces 5 and the disk surface.
As a method for roughing the opposite surfaces 5 of the slider 1, for example, a texturing method is known in which the opposite surfaces 5 are chemically etched or sputtered to form protrusions on the opposite surfaces 5.
However, this method easily damages the thin film element 3 by chemical etching and increases an element recess. An increase in the element recess causes an increase in spacing loss between the thin film element 3 and the disk surface, and deterioration in the efficiency of signal writing and reading sensitivity. In some cases, the thin film element 3 is broken, thereby making normal reading and writing impossible.
The above texturing process is difficult to form protrusions around the thin film element 3 without damaging the thin film element 3. Therefore, no protrusion is formed around the thin film element 3, and thus the thin film element 3 contact directly the disk surface when the hard disk is stopped. When sliding of the hard disk is started, the thin film element 3 is liable to be damaged and worn.
Further, the texturing process requires complicated steps and many steps, and the processing equipment used in the texturing process is very expensive.
The present invention has been achieved for solving the above problems of a conventional magnetic head, and an object of the present invention is to provide a magnetic head which permits easy formation of protrusions on opposite surfaces of a slider using a laser, and particularly a magnetic head which permits formation of protrusions around a thin film element without damage to the thin film element, and a production method thereof.
In order to achieve the object, the present invention provides a magnetic head comprising a slider which contacts the surface of a recording medium when the recording medium is stopped, and which assumes a floating state after the recording medium is started wherein the trailing side end thereof floats or slides on the recording medium due to the floating force of a flow of air on the surface of the recording medium; a magnetic recording and/or reproducing thin film element provided at the trailing side end of the slider; and a protecting film for covering the thin film element; wherein protrusions are formed on the surface of the protecting layer opposite to the recording medium (the face surface) and/or a portion of the face surface of the slider in the vicinity of the trailing side end.
Also protrusions are preferably formed on a portion of the face surface other than the vicinity of the trailing side end.
Further, the protrusions formed in the vicinity of the trailing side end are preferably denser than the protrusions formed on a portion of the opposite surface other than the vicinity of the trailing side end.
Further, the protrusions formed on the protecting layer and the face surface preferably have an average height of 5 to 50 nm.
On the protecting layer and the face surface is preferably formed a hard carbon thin film which is more preferably deposited to a thickness of 5 to 15 nm.
In the present invention, the slider can be formed by using Al2O3xe2x80x94TiC comprising a mixture of Al2O3 (aluminum oxide) crystal grains and TiC (titanium carbide) crystal grains, or Si (silicon).
The present invention also provides a method of producing a magnetic head comprising a slider which is made of a ceramic material, which contacts the surface of a recording medium when the recording medium is stopped, and which assumes a floating state after the recording medium is started wherein the trailing side end thereof floats or slides on the recording medium due to the floating force of a flow of air on the surface of the recording medium; a magnetic recording and/or reproducing thin film element provided at the trailing side end of the slider; and a protecting film for covering the thin film element; the method comprising smoothing face surface of the protecting layer opposite to the recording medium and the face surface of the slider, and then applying a laser beam to at least the protecting layer and/or the trailing side end of the face surface to form protrusions.
After the protrusions are formed, a hard carbon thin film is preferably formed on the face surface of the protecting layer and the face surface.
Since the hard carbon thin film is formed on the protecting layer and the face surface, the protrusions formed on the protecting layer and the face surface are hardly worn even if the slider and the disk surface repeatedly slide on each other.
In the present invention, a Nd-YAG laser can be used as a laser for emitting the laser beam, and a secondary higher harmonic or quaternary higher harmonic can be used as the laser beam of the Nd-YAG laser.
As the laser for emitting the laser beam, an excimer layer can also be used.
In the present invention, the protrusions are formed on at least the protecting layer around the thin film element and/or a portion of the face surface of the slider in the vicinity of the trailing side end thereof so that the thin film element does not contact directly the disk surface. Therefore, even if the slider and the disk surface repeatedly slide on each other, the thin film element is protected by the protrusions, thereby hardly causing the problem of breaking the thin film element.
Also, in the present invention, the laser beam is applied to the face surface of the slider and the protecting layer, which are polished, to form the protrusions. The use of the laser facilitates the formation of the protrusions, and facilitates the formation of the protrusions in any desired region. It is thus possible to easily form the protrusions around the thin film element without damaging the thin film element. In addition, since neither mechanical stress nor thermal stress is applied to the face surface of the slider and the periphery of the thin film element during laser processing, neither crack nor strain in a junction occurs. It is also possible to arbitrarily change the shape of the protrusions and the average height thereof by appropriately selecting the type of the laser used and the output of the laser beam.
Although, when the slider is in a floating state, the trailing side end thereof with the thin film element provided floats or slides on the recording medium, but the sliding may be either continuous or incontinuous.